Tunnel kiln



III III II llllJ V INVENTOR I m :ifiiiil u. i

.J. FETZER TUNNEL KILN Filed Jan. 11, 1930 Nov. 1, 1932.

Patented Nov. 1, 1932 UNITED STATES JOHN FETZER, F PITTSBURGH, PENNSYLVANIA TUNNEL KILN Application filed January 11, 1930. Serial No. 420,107.

feature as will be more fully explained here-.

inafter. 1 7

It is'among theobjects of this invention to provide a method of and apparatus for drying, firing and cooling clay articles adapted to carry out the severalsteps 0f the process in a minimum period of time andby the use of a minimum length of. kiln whereby great economy of heat energy or fuelis obtained.

' Another object ofthe invention is the pro vision of means forproducing uniform application of heat to all articles passing through the kiln whereby uniformity in the quality of the product is obtained.

Another object of the invention is the provision of a kiln which is adapted to dry, 'fire and cool the articles passing therethrough at a maximum rate without distorting or'unduly warping or stressing the articles, whereby a. maximum production capacity is obtained from a kiln of a given cross sectional area and length.

These and other objects will become more apparent from a consideration of the accompanying drawing inwhichlikereferencecharacters designate like parts and in which Fig. 1 is a top elevational view partly in section of a kiln embodying the principlesherein set forth; Fig. 2 a sideelevational view thereof partly in section; Fig. 3 a cross sectional view taken along the lines IIIIII of Fig.- 1; and Figs. a and 5 are top and side elevational views of a portion of the roof showing its holr low'tile construction. Referring to Figs. 1 and 2 of the drawing, the structure therein illustrated comprises a tunnel kiln 1 having doors 2 at each. end.

The kiln is provided with baflie plates 3 and 4 at the sides and top, respectively, to form 0 a plurality...of chambers. The plates are hinged in a suitable manner to swing in the direction of movement of the work which is towards the rear of the kiln, and they. are provided with springs 5 or other suitable means tending to. hold them transversely of the GDP and side walls. -Handles 6 are attached to i the plates and extend through. the kiln wall for the manual operation. of the plates when desired. A plurality of openings shown by dotted lines 7 and provided withcovers 8 are located in the side walls sothat the articles passing through the kiln may be inspectedfrom time to time. At 9, are a number of openings leading through the kiln walls to as.

many ash pits shown by dotted lineslO, said 5 if ash pits having covers 11 for the ready removal of ashes without interference with the operation of the kiln. Atboth sides of Fig.

1 are fire boxes 12 shown in side elevation in Fig. 3. An air blower 13is mounted at the rear of the kiln and is providedwith a pulley l i'for connection with a prime mover, such 7 as a motor (not shown). A hopper-leer tends across the top of the kiln and is pro? vided with a feed mechanism 16, to supply powderedfuel to the insideof the kiln. An exhaust, fan 17 draws the products of com bustion to the front end of the kiln. V

Throughout the length of the kiin is'a track 18, Figs. 2 and 8, whichzis elevated at :89

the front end to provide adeclining runway towards the discharge end of the kiln; Wheeled trucks 19 constitute the work sup} ports and the trucks are arranged end to end to form a continuous conveyor for the articles passing through the kiln.

WVhen a truckloadof articles is charged into the kiln at the front end,a truckload offirecl articles is simultaneously discharged 90 at the rear end. Since the connected truck bodies form a passage along the entire length of the kiln, baffle plates 20 are provided underneath the trucks, to prevent such passage operating as. a flue. The plates 20 extend across the entire width of the kilnbetween the side plates 21 of the trucks, Fig. 3, and to the-bottom or floor 22. In this manner they function. to scrape the bottom and prevent accumulation of ashes Whichare scraped into above the trucks 19 and is arranged in staggered relation forming a checker workof fiues. The truck bodies are provided with fire clay or brick bottom 23 F ig. 8, on which .the articles to be fired are stacked.

The operation of the kiln in the'firing of the brick orother clay articles'mounted on the movable conveyers, asdescribed, is briefly as follows Combustiton is established in the fire boxes 12 and articles to be fired are charged into the front end of the kiln and are moved toward the discharge end in the direction of the ,tutes the firing chamber. 17 is operated to set up a draft from the firing fire boxes. As the articles to be fired accumulate rather slowly and are intermittently charged into the kiln, the trucks will move slowly to the portion of the kiln between the battle members 3 and 4. This portion consti- The exhaust fan chamber through the checkerwork of brick toward the charging end of the kiln whereby the green clay is subjected toadrying temperature and is preheated preliminary to its passing into the firing chamberbetween the spaced bafiles.

.- When the kiln has been filled to the extent that the charge approaches the fire boxes 12, theclay articles have attained a red heat and combustion may be maintained by feeding powdered fuel through the feed mechanism 16 of thehopper 15 directly on the loaded trucks and the fire box may be extinguished. The feed mechanism 16'may bemechanically operated by a suitable driving mechanism (not shown). ,When the charge of'the kiln advances beyond the fireboxes into the end chamber, the blower 13 may be operated to force a supply of air through the checkerwork or fines of the hot brick into thefiring chamber. The air from the blower cools the brick and is preheated before passing into the firing chamber to support combustion, and as previously explained, the products of combustion are drawn through the checkerwork of the incoming brick by the exhaust fan 17 to dry and preheat'said brick. It is obvious that the same effect can he produced byopening the doors at the respective endsof the kiln to setup a draft through the entire chamber from the discharge end to the charging end, this being possible for the reason that the charging end is slightly elevated as previously explained to provide for the movement of the charge through the kiln by gravity and the circulation is further estab lished for the reason that the articles are hot at the discharge end of the kiln and cold at the charge end, thereby inducing circulation or draft from the hot end to the cold end. However, the use of the blower and exhaust fans is preferred as a means of obtaining positive regulation.

' Byarranging the articles in staggered relation to form a series of fiues in the heated chamber of the kiln, such articles may be continuously fired in a minimum length of time 'and'with uniformity of quality. It is further evident that by utilizing the heat of the the time offiringand cooling the brick is reduced to a minimum.

It is furtherevident that such kilns may be advantageously utilized the firing. of clayarticles of various description, though more particularly for firing brick, tile and the like, which more readily permit stacking to' form the aforementioned checkerwork formation. 1

Although one embodiment of the invention has been herein illustrated and described, it will be obvious to'those. skilled in the art that various modifications may be made in the details of construction, for example in the substitution of the work carrying means or the substitution of other parts than those specified, without departing from the principles herein set forth. V

' I claim herein as my invention: V

1. In a tunnel kiln for firing clay articles, a longitudinal chamber having endclosures, a plurality of wheeled trucks for supporting the articles in theirpassage through said chainber, baffles depending from the trucks to the bottom of said chamber, and bafiles projecting fromithe top and sidewalls of the chamber, said baflies dividing said chamber into separate heating and cooling zones 2. In a tunnel kiln, a heating chamber, conveying means in said chamber, a plurality of ash-pits in spaced relation in the floor of-sa-id chamber and means movable with said conveying means for cooperation with the floor of said chamber to discharge the ashes accumulating on said floor into said pits.

support the articles to be treated thereon in V a-manner to substantially fill said chamber,

a combustion zone in the firing portion of sa1d chamber, means for drawing air into the cooling zone of the 'chamberin contact with the heated articles and conducting said preheated air to the combustion or firing zone and means for drawing the products of combustion through and around the articles being treated towards the charging or drying zone of said chamber, said cooling air and products of combustion being drawn continuously through the treating portion of said chamber in contact with the articles to be treated.

4. In a tunnel kiln for firing clay articles, a longitudinal chamber, a yielding bafiie disposed therein dividing it into a drying, firing and cooling chamber, combustion chambers provided externally of said treating chamber intermediate the preheating and cooling chambers, and a hopper disposed at the top of said treating chamber to feed fuel on the material passing through said chamber, means for drawing air around the heated articles at the cooling end ofsaid chamber andconducting the preheated airto support combustion in the firing chamber and independent means for withdrawing the products of combustion through the preheating chamber.

In testimony whereof I have hereunto set my hand this 10 day of January, 1930. JOHN FETZER. 

